package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.dto.ScrollResult;
import com.hmdp.dto.UserDTO;
import com.hmdp.entity.Blog;
import com.hmdp.entity.Follow;
import com.hmdp.entity.User;
import com.hmdp.mapper.BlogMapper;
import com.hmdp.service.IBlogService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.service.IFollowService;
import com.hmdp.service.IUserService;
import com.hmdp.utils.SystemConstants;
import com.hmdp.utils.UserHolder;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ZSetOperations;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

import static com.hmdp.utils.RedisConstants.BLOG_LIKED_KEY;
import static com.hmdp.utils.RedisConstants.FEED_KEY;

/**
 * <p>
 *  服务实现类
 * </p>
 */
@Service
public class BlogServiceImpl extends ServiceImpl<BlogMapper, Blog> implements IBlogService {

    @Resource
    private  IUserService userService;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private IFollowService followService;

    @Override
    public Result queryHotBlog(Integer current) {
        // 根据用户查询
        Page<Blog> page = query()
                .orderByDesc("liked")
                .page(new Page<>(current, SystemConstants.MAX_PAGE_SIZE));
        // 获取当前页数据
        List<Blog> records = page.getRecords();
        // 查询用户
        records.forEach(blog ->{
            this.queryBlogUser(blog);
            this.isBlogLiked(blog);
        });
        return Result.ok(records);
    }

    /**
     * 根据id查询笔记
     * @param id 笔记id
     * @return 无
     */
    @Override
    public Result queryBlockById(Long id) {
        Blog blog = getById(id);
        
        if (blog == null) {
            return Result.fail("博客不存在");
        }

        //查询用户
        queryBlogUser(blog);
        //查询blog是否被点赞
        isBlogLiked(blog);
        return Result.ok(blog);
    }

    /**
     * 判断blog是否被点赞 并设置isLiked值
     * @param blog 笔记
     */
    private void isBlogLiked(Blog blog) {
        //1.获取登录用户
        UserDTO user = UserHolder.getUser();
        if (user == null){
            log.error("用户为空，不能判断是否点赞");
            return;
        }
        Long userId = user.getId();
        //2.判断当前用户是否已经点赞
        Double score = stringRedisTemplate.opsForZSet().score(BLOG_LIKED_KEY + blog.getId(), userId.toString());
        blog.setIsLike(score != null);
    }

    /**
     * 查询笔记用户
     * @param blog 笔记
     */
    private void queryBlogUser(Blog blog) {
        Long userId = blog.getUserId();
        User user = userService.getById(userId);
        blog.setName(user.getNickName());
        blog.setIcon(user.getIcon());

    }

    /**
     * 判断点赞数量，确保点一赞
     * @param id 用户id
     * @return 无
     */
    @Override
    public Result likeBlog(Long id) {
        //1.获取用户id
        Long userId = UserHolder.getUser().getId();
        String key = BLOG_LIKED_KEY + id;

        //TODO ====存在并发问题
        //2.判断是否点过赞
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        //TODO 存在事务问题====
        if (score == null){
            //3.1.未点赞，数据库赞 + 1
            boolean isSuccess = update().setSql("liked = liked + 1").eq("id", id).update();
            if (isSuccess){
                //3.2.保存用户到redis的set集合 zadd key value score
                stringRedisTemplate.opsForZSet().add(key,userId.toString(),System.currentTimeMillis());
            }

        }else {
            //4.1.点赞，数据库赞 - 1
            //4.2.把用户从redis的set里移除
            boolean isSuccess = update().setSql("liked = liked - 1").eq("id", id).update();
            if (isSuccess){
                stringRedisTemplate.opsForZSet().remove(key,userId.toString());
            }
        }
        return Result.ok();
    }

    /**
     * 查询top5的用户
     * @param id 笔记id
     * @return 无
     */
    @Override
    public Result queryBlockLikes(Long id) {
        //1.查询top5的点赞用户 zrange key 0 4
        Set<String> top5 = stringRedisTemplate.opsForZSet().range(BLOG_LIKED_KEY + id, 0, 4);
        if (top5 == null || top5.isEmpty()){
            return Result.ok(Collections.emptyList());
        }
        //2.解析出用户id
        List<Long> ids = top5.stream().map(Long::valueOf).collect(Collectors.toList());
        
        //3.更具用户id 查询用户
        String idStr = StrUtil.join(",",ids);
        List<UserDTO> userDTOS = userService.query()
                .in("id",ids).last("order by field (id," + idStr +")").list()
                .stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());

        //4.返回
        return Result.ok(userDTOS);
    }

    /**
     * 保存笔记 并进行关注推送
     * @param blog 笔记
     * @return 笔记id
     */
    @Override
    public Result saveBlog(Blog blog) {
        //1. 获取登录用户
        UserDTO user = UserHolder.getUser();
        blog.setUserId(user.getId());

        //2. 保存探店博文
        boolean result = save(blog);
        if (!result){
            return Result.fail("新增笔记失败");
        }

        //3. 查询笔记作者的所有粉丝
        List<Follow> follows = followService.query().eq("follow_user_id", user.getId()).list();

        //4. 推送笔记id给所有粉丝 每个粉丝都有粉丝收件箱
        for (Follow follow : follows) {
            //4.1.获取粉丝id
            Long userId = follow.getUserId();
            //4.2.推送
            String key = "feed:" + userId;
            stringRedisTemplate.opsForZSet().add(key, String.valueOf(blog.getId()),System.currentTimeMillis());

        }

        return Result.ok(blog.getId());
    }


    /**
     * 实现关注推送页码的分页实现
     * @param max 上一次查询的最小时间戳
     * @param offset 偏移量
     * @return
     */
    @Override
    public Result queryBlogOfFollow(Long max, Integer offset) {
        //1.获取当前用户
        Long userId = UserHolder.getUser().getId();
        String key = FEED_KEY + userId;

        //2.查询收件箱 ZREVRANGEBYSCORE key Max Min LIMIT offset count
        Set<ZSetOperations.TypedTuple<String>> typedTuples = stringRedisTemplate.opsForZSet()
                .reverseRangeByScoreWithScores(key, 0, max, offset, 3);

        if (typedTuples == null || typedTuples.isEmpty()){
            return Result.ok();
        }
        //3.解析数据：blogId minTime（时间戳）offset
        List<Long> ids = new ArrayList<>(typedTuples.size());
        long minTime = 0;
        int os = 1;
        for (ZSetOperations.TypedTuple<String> tuple : typedTuples) {
            //3.1.获取id
            ids.add(Long.valueOf(tuple.getValue()));
            //3.2.获取分数
            long time = tuple.getScore().longValue();
            if (time == minTime){
                os++;
            }else {
                minTime = time;
            }
        }


        //4.根据id查询blog
        String idStr = StrUtil.join(",", ids);
        List<Blog> blogs = query().in("id",ids).last("order by field (id," + idStr + ")").list();

        for (Blog blog : blogs) {
            //查询blog有关的用户
            queryBlogUser(blog);
            //查询blog是否被点赞
            isBlogLiked(blog);
        }

        //5.封装返回
        ScrollResult result = new ScrollResult();
        result.setList(blogs);
        result.setOffset(os);
        result.setMinTime(minTime);
        return Result.ok(result);
    }
}
